The U.S. Park Police flying over the Potomac River. The Pentagon will be charged with tracking helicopter noise in the Washington, D.C. area under provisions of the recently enacted National Defense Authorization Act. The provision in the massive $740 billion legislation was inserted at the behest of several D.C.-area congressmen who have long lamented the steady rotor din over the nation’s capital and surrounding suburbs. But what all this data will actually accomplish remains to be seen. As in the Los Angeles Basin, the competing pressures of crowded airspace and the aviation needs of public safety and law enforcement limit practical—and safe—options.